The present invention relates to devices for suspending a vibrating structure on a rigid support structure, in particular for suspending an exhaust pipe of a motor vehicle on the body of the latter.
More specifically, the invention relates to a device for suspending a vibrating structure on a rigid support structure comprising:
an annular elastic element comprising two fixing members designed to be linked respectively to two structures, said fixing members being spaced apart from one another in what is referred to as a vibration direction and being linked to one another by two elastomer branches extending substantially in the vibration direction,
and at least one vibrating mass, designed to filter high frequency vibrations, linking said branches to one another.
A known device of this type is illustrated in FIG. 1 of the appended drawings, whilst FIG. 2 provides a theoretical equivalent diagram of this device and FIG. 3 a diagram of the stiffness K obtained as a function of the frequency f of the vibrations acting between the fixing members 1 and 2 of the elastic element A of the device, which is made from rubber for example. As illustrated in FIG. 2, each elastomer branch 3 may be a spring R and a damper C mounted in series between the body 20 of a motor vehicle and its exhaust pipe 21, the vibrating mass M being linked to the two branches 3 between their respective spring R and damper C. The purpose of this known technique is illustrated in FIG. 3 and resides in the filtering of high frequency vibrations, made possible by incorporating the vibrating mass M.
The disadvantage of this device essentially resides in the fact that it does not allow displacements of the vibrating structure relative to the rigid support structure to be limited when the rigid structure is subjected to very high traction forces, particularly in the vertical direction. As a result, there is a risk that the elastic device will deteriorate.
Another disadvantage of this device resides in the shape of the mass M and its relative disposition with respect to the device. As may be seen from FIG. 1, the mass M is provided in the form of a rigid bar, the two opposite ends of which are embedded respectively in the two branches 3 of the elastic element A. Consequently, the two branches are no longer continuous, which tends to impair the fatigue strength of the device.
The objective of the present invention in particular is to remedy these drawbacks.
To this end, the suspension device proposed by the invention is characterised in that the vibrating mass is provided in the form of a ring, which encloses the elastic element so as to form two stop zones located respectively in the vicinity of the two fixing members in order to restrict displacements of the latter under traction.
Displacements of the vibrating structure under traction relative to the rigid support structure are therefore perfectly limited by the shape and disposition of said vibrating mass and the device is also very easy and inexpensive to manufacture.
In preferred embodiments of the suspension device proposed by the invention, one and/or the other of the following features may also be incorporated:
the elastic element comprises an elastomer block, provided with a recess defining firstly one of said branches of the elastic element and secondly two compression stop zones directed one towards the other on a level with the fixing members;
the vibrating mass has two sections which run respectively alongside the two branches of the elastic element, each being provided with a projection oriented in the direction of the elastic element, said ring being linked to the elastic element by over moulding and each of said branches of the elastic element being adhered respectively to each of said projections;
the vibrating mass is metallic;
the vibrating mass is covered with an elastomer layer made in one piece with the elastic element;
the elastomer layer completely encases the vibrating mass.
Other features and advantages of the invention will become clear from the following description of one of its embodiments, given by way of illustration only and not restrictive in any respect, and with reference to the appended drawings.